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After breathing in a test tube that contains acidified K\(_2\)Cr\(_2\)O\(_7\), a man noticed the change...

Chemistry
JAMB 2024

After breathing in a test tube that contains acidified K\(_2\)Cr\(_2\)O\(_7\), a man noticed the change in the colour of K\(_2\)Cr\(_2\)O\(_7\) from orange to green. This suggests the presence of

  • A. alkanone
  • B. alkanal
  • C. alkanol
  • D. alkanoic acid
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Correct Answer: Option C
Explanation

When an alcohol is oxidized in a warm solution of potassium dichromate (VI) and dilute sulphuric acid, the solution changes colour from orange to green. This is because the Cr\(_2\)O\(_7\)\(^{2-}\) ions in the solution are reduced to Cr\(^{3+}\) ions. This colour change can be used to identify alcohols. Only alcohols will cause the solution to change colour from orange to green.

There is an explanation video available below.


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Explanation Video

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